Process of recovering partially-hydrated cellulose esters from photographic films.



s'rn rns PATENT-curios;

GEORGE w; MILES, DYE-BELMONT; mn'ssncnus'nrrs, Assrenonro EAs'rMAiI xonnx "COMPANY, OF ROCHESTER, NEW YORK, A OORIORATI ON OF NEW YORK.

rnocnss orniicov'nnme rnnrmnnY-nxnna'rn'n onLLUL'osn nsrnns FROM rr'ro'roennrnxe FILMS. a a

,19 ,799.. Ho Drawing.

To all whom may concern:

Be it known that I, GEORGE W." .ll/Inins, a citizen of the United States, residin at Belmont, county of Middl'eSex, and tate of Massachusetts, haveinvented certain new anduseful Improvements in vProcesses: of'

' Recovering Partial1y-1 Iydrated Cellulose scribed and -Esters 'from'Pho tographic Films, fully derepresented in. the following specification;

My' invention relates ticularly the-v cellulose derivative descri ed and claimed Letters Patent of'the United v States N 0. 838,350, granted .to me December 11,1906, of which a characteristic, example i a partially hydrated, cellulose acetate. r

1 One object of my invention is to recoverreadily and inexpensively and in useful form, 'such. an acetate which pgmprises -inj part a photographic film, foi""'"ins'tance,- a

ymo'vingplcture film which is defective or lose -acetate, and inthecase of a photohas become worn,out; Photographic films, of this character. 'carrya film of gelatin 'orglue closely'adhering to the cellulose ace- .tate ribbon and in order to utilize the ace'-.

graphic film accomplish a this separation from the glue film by'm'eans of a solvent l composed of benz oland any of the ordinary commercial alcohols, such as denatured al-' coh ol'or wood alcohol, thebenzol and alcohol being mixed in about equal proportions by volume. I heat this liquid mixture pref-.' erably to about 60 C. 40

boiling point of the liquid) with thephotographic" films, composed for example ofa ribbon of partially hydrated cellulose ace;

tate and an adherent film of glue.' The cel-' lulose derivative goes into solution leaving the glue film undissolved. This glue film, being heavier than the liquid, andnow unattached to-thecellulose ester, tends to'set- -tle' to the bottom of the vessel if not dis:

" turbed, where it forms a morefor 'less,co-,v herent mass which may, lf de'sired, befur v i ther manipulated as by rolling it -up into v {a ball and then separatedfrom the solution. that it assists the alcohol to complete the" Specificati'on of Letters Patent. Patented Application filed March 27, i914. Serial No. 827,716.

to the treatmentof films composed of cellulose derivatives,v ar-' (and not over the Sept. 5,1916.

The glue may be removed by various well known methods as filtering,settling. or decanting, the solution being in the' ordinary case the only part that it is necessary topreserve. I then cool the solution, when the cellulose "derivative, precipitates. If the totaljquantity ofglue-ha's not beenjremoved i in the previous operation, Qsojthat some re-' mains either entrained'by the-" liquid and, i

precipitate or dissolved 'infthesolvent, fur:-

ther 'purificationis necessary; If 'conven-' ient, 'at'this stage, a part ofthe glue which remains-as for example on the vessel walls oras small-particles in the liquid, may be mechanically removed, especially where coherent masses are present 'andcan be easily lifted "out or otherwise separated from-the 3 solution. The greater .bulk of the liquid is then expressedfrom. the precipitate in a filter'press; The remainder of the solvent y which 'is'retained in. contact with the precipitated partiallyhydrated cellulose ace- I .tate,.I may then recover by any ordinary method such as distillation. 1

Subsequent washing of the precipitated cellulose derivative in water will remove any trace or remainder of the glue which may have been'dissolved in the solution or "which in any way remains with the precipi This leaves the partially hydrated acetate in perfect condition to be placed in solution for the purpose of manufacturing film's. v I

' 'As a quick and efi'ective method of carry- I ing out my invention, I separate the 'cellulose esters from the glue by filtering the solution 'while. it isstill warm enough to hold the esters in solution, thus removing all the 'glue except that which may have been dissolved. thereafter precipitate the esters by cooling and separate the precipitate .from the solvent and otherwise further treatit as' above described.

A characteristic of partially hydrated cellulose acetate such as described in my patent aforesaid, is'that it becomes plastic in the ordinary alcohols (including glycerin) at elevated temperatures andit is believed that the addition of benzol 'toalcohol enables a complete solution of the partially hydrated cellulose acetate-to-be made in otherwords Work which th alcoholalone can (mi para;

tially accomplish.

. a What I. claim and desire to secure Iietters'"Patent is .i I, 1. The process of recovering partially hydrated cellulose acetate from films having a colloidal material associated therewith. which consists in dissolving the acetate'ins 2. Theprocess of removing partially hydrated cellulose acetate from photographic films, comprising said cellulose 'derivative and an adherent, glue, which cons sts in dissolving the-cellulose derivative in amixture of benz'ol and alcohol leaving the 'gluezsubstantially undissolved; isolating the cellu lose derivative from'a the undissolved glue,

cooling the solution and thereby precipi-o,

ta'tin'g the gcellulose derivative and recover- V-ing the, precipitate. r

3. The process of recovering partially by drated' cellulose acetate from photographic lfilms which comprise said cellulose derivative andran adherent glue, which consists in dissolving the cellulose derivative in a hot mixture of'benzol and alcohol, leaving the glue substantially undissolved, filtering the solution while hot to remove the glue there- "from,'i' c'o'o1ing the solution and precipitating out the cellulose derivative recovering :the

solvent from the precipitate and'washing the precipitate with water to'remove any,

traces of glue'that rem ain.- v

In testimonywhereof, I havehereunto set n y hand, thepresence of'two subscribingwitnes'ses. o. GEORGE wJMILEs. Witnesses? J. A. V GRAVES AJ Z.BERTVE. PARKER. 

